JP6689057B2 - Optical glass, preforms and optical elements - Google Patents

Description

  The present invention relates to an optical glass, a preform and an optical element.

  In recent years, digitalization and high definition of devices using an optical system have been rapidly advanced, and various optical devices such as photographing devices such as digital cameras and video cameras and image reproducing (projection) devices such as projectors and projection TVs. In the field, there is an increasing demand for reducing the number of optical elements such as lenses and prisms used in the optical system and reducing the weight and size of the entire optical system.

Among optical glasses for producing an optical element, particularly, it has a high refractive index ( _nd ) of 1.60 or more and 1.80 or less, which can reduce the weight and size of the entire optical system, and 40 or more and 60 or more. The demand for high-refractive-index, low-dispersion glasses having the following high Abbe numbers (ν _d ) is very high. As such a high-refractive-index, low-dispersion glass, a glass composition represented by Patent Document 1 is known.

JP, 2003-020249, A

  In order to reduce the material cost of the optical glass, the raw material cost of the optical glass is desired to be as low as possible. However, it is hard to say that the glass described in Patent Document 1 can sufficiently meet such requirements.

Further, the glass described in Patent Document 1 has a problem that the specific gravity of the glass is large and the mass of the optical element is large. That is, when these glasses are used in an optical device such as a camera or a projector, there is a problem that the mass of the entire optical device tends to increase.
However, although the glass disclosed in Patent Document 1 has a high refractive index and low dispersion, it has a high glass transition point and cannot be said to be a glass suitable for press molding. Further, the glass disclosed in Patent Document 1 cannot be said to have high stability, and devitrification or the like may occur.

  On the other hand, even when the material cost of the optical glass is reduced and the glass transition point is lowered, the optical glass is required to have high stability and be resistant to devitrification.

The present invention was made in view of the above problems, and an object thereof is to provide a refractive index (n _d) and Abbe number ([nu _d) is within a desired range and stability To obtain a high optical glass at a lower cost.

Further, the present invention has an object to obtain an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, high stability, and a low glass transition point, which is suitable for press molding. And

In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive studies to find that the content of the expensive Ta ₂ O ₅ component in the glass containing the B ₂ O ₃ component and the Ln ₂ O ₃ component is high. The inventors have found that a glass having a desired high refractive index and low dispersion and high stability can be obtained even when the amount is small, and have completed the present invention.
Specifically, the present invention provides the following.

(1) in mole percent on the oxide _basis, B 2 _{O 3} ingredient 25.0% or more 70.0 or less, _Ln 2 _{O 3} ingredient 3.0% 20.0% or less (wherein, Ln is One or more selected from the group consisting of La, Gd, Y and Yb), the content of the Ta ₂ O ₅ component is less than 5.0%, and the refractive index of 1.60 or more and 1.80 or less ( nd), and an optical glass having an Abbe number (νd) of 40 or more and 60 or less.

(2) In mol% based on oxide,
La ₂ O ₃ component 0 to 20.0%,
SiO ₂ component 0 to 20.0%,
Li ₂ O component 0 to 20.0%,
ZnO component 0-25.0%
ZrO ₂ component 0 to 10.0%
(1) The optical glass as described in (1).

(3) In mol% based on oxide,
Gd ₂ O ₃ component 0 to 10.0%,
Y ₂ O ₃ component 0 to 15.0%,
Yb ₂ O ₃ component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 10.0%,
MgO component 0 to 10.0%,
CaO component 0 to 10.0%,
SrO component 0 to 10.0%,
BaO component 0 to 10.0%,
TiO ₂ component 0 to 20.0%,
Nb ₂ O ₅ component 0 to 15.0%,
WO ₃ component 0 to 10.0%,
P ₂ O ₅ component 0 to 15.0%,
GeO ₂ component 0 to 15.0%,
Al ₂ O ₃ component 0 to 15.0%,
Ga ₂ O ₃ component 0 to 15.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ component 0 to 15.0%,
SnO ₂ component 0-5.0% and Sb ₂ O ₃ component 0-1.0%
The optical glass as described in (1) or (2) above.

(4) The optical glass according to any one of (1) to (3), wherein the oxide-based molar sum (B ₂ O ₃ + SiO ₂ ) is 30.0% or more and 75.0% or less.

(5) The molar sum of the Rn ₂ O components (wherein Rn is at least one selected from the group consisting of Li, Na, and K) based on the oxide is 20.0% or less,
The optical component according to any one of (1) to (4), wherein the RO component (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) has a molar sum of 10.0% or less. Glass.

(6) The optical glass according to any one of (1) to (5), wherein the oxide-based molar sum (RO + Rn ₂ O) is 5.0% or more and 25.0% or less (wherein Rn is Li or Na). , K, and R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba).

  (7) The optical glass according to any one of (1) to (6), wherein the oxide-based molar ratio ZnO / (ZnO + RO) is 0.50 or more (in the formula, R is Mg, Ca, Sr, or Ba). One or more selected from the group).

(8) The optical glass according to any one of (1) to (7), wherein the oxide-based molar sum (ZnO + ZrO ₂ ) is 10.0% or more and 35.0% or less.

(9) The optical glass according to any one of (1) to (8), wherein the oxide-based molar sum (ZnO + Li ₂ O) is 10.0% or more and 40.0% or less.

  (10) The optical glass according to any one of (1) to (9), which has a glass transition point (Tg) of 600 ° C. or lower.

  (11) An optical element comprising the optical glass according to any one of (1) to (10).

  (12) A preform for polishing and / or precision press molding, which is made of the optical glass according to any one of (1) to (10).

  (13) An optical element obtained by precision pressing the preform according to (12).

According to the present invention, there refractive index (n _d) and Abbe number ([nu _d) is within a desired range, and can be a highly stable optical glass, obtained cheaper.
Further, according to the present invention, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges, high stability, and a low glass transition point and suitable for press molding can be obtained. You can also

It is a figure which shows the refractive index (nd) about the glass of the Example of this application, and the relationship of Abbe's number ((nu) _d ).

The optical glass of the present invention has a B ₂ O ₃ component content of 25.0% or more and 70.0% or less and an Ln ₂ O ₃ component content of 5.0% or more and 15.0% or less (equation: mol% based on oxide) Ln is at least one selected from the group consisting of La, Gd, Y, and Yb), and the content of the Ta ₂ O ₅ component is less than 5.0%, 1.60 or more and 1.80 or less. And has an Abbe number (νd) of 40 or more and 60 or less. According to the present invention, in a glass containing a B ₂ O ₃ component and an Ln ₂ O ₃ component, a desired high refractive index and low dispersion can be obtained even when the content of an expensive Ta ₂ O ₅ component is small. A glass having a high stability is obtained. Therefore, an optical glass having a refractive index (n _d ) and an Abbe number (ν _d ) within desired ranges and high stability can be obtained at a lower cost.

  Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and is carried out with appropriate modifications within the scope of the object of the present invention. be able to. It should be noted that the description of the overlapping description may be omitted as appropriate, but the gist of the invention is not limited thereto.

[Glass component]
The composition range of each component constituting the optical glass of the present invention will be described below. In the present specification, unless otherwise specified, the content of each component is expressed in mol% based on the oxide. Here, the composition of "oxide standard" is the total amount of the produced oxides, assuming that all oxides, complex salts, fluorides, etc. used as glass raw materials are decomposed to change into oxides when melted. It is a composition in which each component contained in the glass is described with the number of moles being 100 mol%.

<About essential and optional components>
The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide in the optical glass of the present invention containing a large amount of rare earth oxide.
In particular, when the B ₂ O ₃ component is contained in an amount of 25.0% or more, the devitrification resistance of the glass can be enhanced, the Abbe number can be increased, and the specific gravity can be reduced. Therefore, the content of the B ₂ O ₃ component is preferably 25.0%, more preferably 30.0%, further preferably 40.0%, further preferably 44.0%, further preferably 47.0%. Is the lower limit.
On the other hand, by setting the content of the B ₂ O ₃ component to 70.0% or less, it is possible to suppress the decrease in the refractive index and the deterioration in the chemical durability. Therefore, the content of the B ₂ O ₃ component is preferably 70.0%, more preferably 65.0%, further preferably 60.0%, further preferably less than 55.0%.
As the B ₂ O ₃ component, H ₃ BO ₃ , Na ₂ B ₄ O ₇ , Na ₂ B ₄ O ₇ · 10H ₂ O, BPO ₄ or the like can be used as a raw material.

The sum (molar sum) of the contents of the Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of La, Gd, Y, and Yb) is 3.0% or more and 20.0% or less. Is.
In particular, by setting the molar sum to 3.0% or more, the refractive index and Abbe number of the glass can be increased, so that it is possible to easily obtain a high refractive index and low dispersion glass. Therefore, the lower limit of the molar sum of the Ln ₂ O ₃ component contents is preferably 3.0%, more preferably 5.0%, and further preferably 7.0%.
On the other hand, by setting this molar sum to 20.0% or less, the liquidus temperature of the glass becomes low, so that the devitrification resistance can be enhanced. Further, this can reduce the material cost of the glass. Therefore, the molar sum of the contents of the Ln ₂ O ₃ components is preferably 20.0% or less, more preferably less than 17.0%, further preferably less than 14.0%, further preferably less than 11.0%, More preferably, it is less than 10.0%.

The Ta ₂ O ₅ component is an optional component that can increase the refractive index, the devitrification resistance, and the viscosity of the molten glass when the content exceeds 0%.
On the other hand, when the content of the Ta ₂ O ₅ component is less than 5.0%, the amount of the Ta ₂ O ₅ component, which is a rare mineral resource, used is reduced, so that the glass material cost can be reduced. Further, this can reduce the specific gravity. Therefore, the content of the Ta ₂ O ₅ component is preferably less than 5.0%, more preferably less than 3.0%, still more preferably less than 1.0%, and further preferably less than 0.1%.
As the Ta ₂ O ₅ component, Ta ₂ O ₅ or the like can be used as a raw material.

The La ₂ O ₃ component is an optional component capable of increasing the refractive index of glass and reducing dispersion (increasing the Abbe number). Further, by containing the La ₂ O ₃ component, the contents of other rare earth elements that increase the specific gravity are reduced, so that it is possible to easily obtain a glass having a small specific gravity. Therefore, the content of the La ₂ O ₃ component may preferably have a lower limit of more than 0%, more preferably 1.0%, further preferably 4.0%, and further preferably 6.0%.
On the other hand, when the content of the La ₂ O ₃ component is set to 20.0% or less, the stability of the glass can be increased, devitrification can be reduced, and the increase in Abbe number can be suppressed. Therefore, the content of the La ₂ O ₃ component is preferably 20.0% or less, more preferably less than 17.0%, further preferably less than 14.0%, further preferably less than 11.0%, further preferably It is less than 9.0%.
As the La ₂ O ₃ component, La ₂ O ₃ , La (NO ₃ ) ₃ .XH ₂ O (X is an arbitrary integer) or the like can be used as a raw material.

The SiO ₂ component is an optional component capable of increasing the viscosity of the molten glass, reducing the coloring of the glass, and enhancing the devitrification resistance when the content exceeds 0%. Therefore, the content of the SiO ₂ component may be preferably more than 0%, more preferably more than 1.0%, still more preferably more than 4.0%, further preferably more than 7.0%.
On the other hand, by setting the content of the SiO ₂ component to 20.0% or less, it is possible to suppress a decrease in the refractive index, suppress an increase in the glass transition point, and reduce the specific gravity. Therefore, the upper limit of the content of the SiO ₂ component is preferably 20.0%, more preferably 15.0%, and further preferably 12.5%.
As the SiO ₂ component, SiO ₂ , K ₂ SiF ₆ , Na ₂ SiF ₆ or the like can be used as a raw material.

The Li ₂ O component is an optional component capable of improving the glass meltability and lowering the glass transition point when the content exceeds 0%. Therefore, the content of the Li ₂ O component is preferably more than 0%, more preferably more than 2.0%, further preferably more than 3.0%, further preferably more than 5.0%, further preferably 6.0. %, More preferably more than 7.0%, further preferably more than 9.0%.
On the other hand, by setting the content of the Li ₂ O component to 20.0% or less, it is possible to reduce the decrease in the refractive index and devitrification, and it is possible to enhance the chemical durability. Moreover, since the viscosity of the molten glass is increased by this, the occurrence of striae in the glass can be reduced. Therefore, the content of the Li ₂ O component is preferably 20.0% or less, more preferably less than 15.0%, and further preferably less than 13.0%.
As the Li ₂ O component, Li ₂ CO ₃ , LiNO ₃ , LiF or the like can be used as a raw material.

The ZnO component is an optional component that can lower the glass transition point, reduce the specific gravity and enhance the chemical durability when the content thereof exceeds 0%. Therefore, the content of the ZnO component is preferably more than 0%, more preferably more than 1.0%, further preferably more than 5.0%, further preferably more than 9.0%, further preferably more than 12.0%. , More preferably more than 14.0%, and further preferably more than 15.7%.
On the other hand, by setting the content of the ZnO component to 25.0% or less, it is possible to reduce the decrease in refractive index and devitrification. Moreover, since the viscosity of the molten glass is increased by this, the occurrence of striae in the glass can be reduced. Therefore, the upper limit of the content of the ZnO component is preferably 25.0%, more preferably 22.0%, further preferably 20.0%, and further preferably 17.0%.
For the ZnO component, ZnO, ZnF ₂ or the like can be used as a raw material.

The ZrO ₂ component is an optional component that can contribute to the high refractive index and low dispersion (high Abbe number) of the glass and can enhance the devitrification resistance when the content thereof exceeds 0%. Therefore, the content of the ZrO ₂ component is preferably more than 0%, more preferably more than 1.0%, still more preferably 2.5% or more, still more preferably 3.7% or more, still more preferably 4.2%. The above may be applied.
On the other hand, by setting the ZrO ₂ component to 10.0% or less, it is possible to suppress the deterioration of the devitrification resistance due to the excessive content. Therefore, the upper limit of the content of the ZrO ₂ component is preferably 10.0%, more preferably 8.0%, further preferably 6.0%, and further preferably 5.0%.
As the ZrO ₂ component, ZrO ₂ , ZrF ₄ or the like can be used as a raw material.

The Gd ₂ O ₃ component is an optional component capable of increasing the refractive index and the Abbe number and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, by setting the content of the Gd ₂ O ₃ component to 10.0% or less, the devitrification resistance can be enhanced and the increase in specific gravity can be suppressed. In particular, the material cost of glass can be suppressed by reducing the content of the Gd ₂ O ₃ component. Therefore, the content of the Gd ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, further preferably less than 1.0%.
For the Gd ₂ O ₃ component, Gd ₂ O ₃ , GdF ₃ or the like can be used as a raw material.

The Y ₂ O ₃ component is an optional component that can increase the refractive index and the Abbe number, reduce the specific gravity, and enhance the devitrification resistance when the content exceeds 0%. Therefore, the content of the Y ₂ O ₃ component may be preferably more than 0%, more preferably more than 0.5%, still more preferably more than 1.0%.
On the other hand, by setting the content of the Y ₂ O ₃ component to 15.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of the Y ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 6.0%, further preferably less than 3.0%.
As the Y ₂ O ₃ component, Y ₂ O ₃ , YF ₃ or the like can be used as a raw material.

The Yb ₂ O ₃ component is an optional component capable of increasing the refractive index and the Abbe number and increasing the devitrification resistance when the content exceeds 0%.
On the other hand, by setting the content of the Yb ₂ O ₃ component to 10.0% or less, devitrification due to excessive content can be reduced, an increase in specific gravity can be suppressed, and the material cost of glass can be suppressed. Therefore, the content of the Yb ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, further preferably less than 1.0%.
For the Yb ₂ O ₃ component, Yb ₂ O ₃ or the like can be used as a raw material.

The Na ₂ O component and the K ₂ O component are optional components capable of improving the meltability of the glass raw material, increasing the devitrification resistance, and lowering the glass transition point when at least one of them exceeds 0%. is there.
On the other hand, by setting the content of each of the Na ₂ O component and the K ₂ O component to 10.0% or less, it is difficult to lower the refractive index and devitrification due to excessive content can be reduced. Therefore, the content of each of the Na ₂ O component and the K ₂ O component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, further preferably 1.0. Less than%.
As the Na ₂ O component and the K ₂ O component, Na ₂ CO ₃ , NaNO ₃ , NaF, Na ₂ SiF ₆ , K ₂ CO ₃ , KNO ₃ , KF, KHF ₂ , K ₂ SiF ₆ or the like may be used as a raw material. it can.

The MgO component, the CaO component, and the SrO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when containing at least one of them in an amount of more than 0%. In particular, the MgO component and the CaO component are components that can reduce the specific gravity by containing them.
On the other hand, by setting the content of each of the MgO component, the SrO component, and the CaO component to 10.0% or less, it is possible to reduce the decrease in the refractive index and the devitrification due to the excessive content of these components. Therefore, the content of each of the MgO component, the SrO component, and the CaO component is preferably 10.0% or less, more preferably less than 8.0%, more preferably 4.5% or less, and further preferably 3.0%. Less than
For the MgO component, CaO component, and SrO component, MgCO ₃ , MgF ₂ , CaCO ₃ , CaF ₂ , Sr (NO ₃ ) ₂ , SrF ₂ or the like can be used as a raw material.

When the content of BaO exceeds 0%, the material cost can be suppressed while increasing the refractive index of glass, and the meltability and devitrification resistance of the glass raw material can be improved.
On the other hand, by setting the content of the BaO component to 10.0% or less, devitrification and increase in specific gravity due to excessive content can be suppressed. Therefore, the content of the BaO component is preferably 10.0% or less, more preferably less than 5.0%, and further preferably less than 3.0%.
As the BaO component, BaCO ₃ , Ba (NO ₃ ) ₂ , BaF ₂ or the like can be used as a raw material.

The TiO ₂ component is an optional component capable of increasing the refractive index, reducing the specific gravity, and enhancing the stability when the content exceeds 0%. Therefore, the content of the TiO ₂ component may be preferably more than 0%, more preferably more than 0.02%.
On the other hand, by setting the content of the TiO ₂ component to 20.0% or less, it is possible to suppress a decrease in Abbe number, increase visible light transmittance, and suppress devitrification due to excessive content. Therefore, the content of the TiO ₂ component is preferably 20.0% or less, more preferably less than 10.0%, and further preferably less than 5.0%.
As the TiO ₂ component, TiO ₂ or the like can be used as a raw material.

The Nb ₂ O ₅ component is an optional component capable of increasing the refractive index of glass and devitrification resistance when it is contained in an amount of more than 0%.
On the other hand, by setting the content of the Nb ₂ O ₅ component to 15.0% or less, it is possible to suppress a decrease in Abbe number, a decrease in devitrification resistance, and a decrease in visible light transmittance due to an excessive content. . Further, this makes it possible to reduce the specific gravity of the glass and suppress the material cost. Therefore, the content of the Nb ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably less than 3.0%.
As the Nb ₂ O ₅ component, Nb ₂ O ₅ or the like can be used as a raw material.

The WO ₃ component is an optional component capable of increasing the refractive index, lowering the glass transition point, and enhancing the devitrification resistance when the content thereof exceeds 0%.
On the other hand, by setting the content of the WO ₃ component to 10.0% or less, it is possible to suppress a decrease in the Abbe number of glass, make it difficult to decrease the visible light transmittance, and suppress the material cost. Therefore, the content of the WO ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, further preferably less than 1.0%.
As the WO ₃ component, WO ₃ or the like can be used as a raw material.

The P ₂ O ₅ component is an optional component that can enhance the devitrification resistance when the content exceeds 0%.
On the other hand, by setting the content of the P ₂ O ₅ component to be 15.0% or less, it is possible to suppress deterioration of the chemical durability of the glass, particularly the water resistance. Therefore, the content of the P ₂ O ₅ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably less than 3.0%.
As the P ₂ O ₅ component, Al (PO ₃ ) ₃ , Ca (PO ₃ ) ₂ , Ba (PO ₃ ) ₂ , BPO ₄ , H ₃ PO ₄ or the like can be used as a raw material.

The GeO ₂ component is an optional component that can increase the refractive index of the glass and the devitrification resistance when the content exceeds 0%.
However, since the raw material price of GeO ₂ is high, the material cost increases when the amount thereof is large, and the cost reduction effect by reducing the Ta ₂ O ₅ component and the like is diminished. Therefore, the content of the GeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably less than 1.0%.
For the GeO ₂ component, GeO ₂ or the like can be used as a raw material.

The Al ₂ O ₃ component and the Ga ₂ O ₃ component are optional components that can enhance the chemical durability and the devitrification resistance when the content exceeds 0%.
On the other hand, by setting the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component to 15.0% or less, devitrification due to excessive content can be reduced. Therefore, the content of each of the Al ₂ O ₃ component and the Ga ₂ O ₃ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably 3%. It is less than 0.0%.
As the Al ₂ O ₃ component and the Ga ₂ O ₃ component, Al ₂ O ₃ , Al (OH) ₃ , AlF ₃ , Ga ₂ O ₃ , Ga (OH) ₃ or the like can be used as a raw material.

The Bi ₂ O ₃ component is an optional component capable of increasing the refractive index and decreasing the glass transition point when the content exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, it is possible to suppress a decrease in the Abbe number of the glass and a decrease in the devitrification resistance, and reduce coloring of the glass to reduce visible light. The transmittance can be increased. Therefore, the content of the Bi ₂ O ₃ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, further preferably less than 1.0%.
For the Bi ₂ O ₃ component, Bi ₂ O ₃ or the like can be used as a raw material.

The TeO ₂ component is an optional component capable of increasing the refractive index and decreasing the glass transition point when the content exceeds 0%.
On the other hand, by setting the content of the TeO ₂ component to 15.0% or less, coloring of the glass can be reduced and the visible light transmittance can be increased. Further, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which a portion in contact with the molten glass is formed of platinum. Therefore, the content of the TeO ₂ component is preferably 15.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably less than 1.0%.
As the TeO ₂ component, TeO ₂ or the like can be used as a raw material.

The SnO ₂ component is an optional component capable of increasing the visible light transmittance of the glass while containing less than 0% while refining by reducing the oxidation of the glass melt.
On the other hand, when the content of the SnO ₂ component is 5.0% or less, coloring of the glass due to reduction of the molten glass and devitrification of the glass can be reduced. Further, the alloying of the SnO ₂ component and the melting equipment (particularly noble metal such as Pt) is reduced, so that the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 5.0%, more preferably 3.0%, further preferably 1.0% as the upper limit, and further preferably less than 0.1%.
For the SnO ₂ component, SnO, SnO ₂ , SnF ₂ , SnF ₄ or the like can be used as a raw material.

The Sb ₂ O ₃ component is an optional component capable of defoaming the glass melt when the content exceeds 0%.
On the other hand, if the amount of Sb ₂ O ₃ is too large, the transmittance in the short wavelength region of the visible light region becomes poor. Therefore, the upper limit of the Sb ₂ O ₃ component content is preferably 1.0%, more preferably 0.5%, and even more preferably 0.3%.
Sb ₂ O ₃ component can be used _{Sb 2 O 3, Sb 2 O} 5, Na 2 H 2 Sb 2 O 7 · 5H 2 O and the like as raw materials.

The component for clarifying and defoaming the glass is not limited to the above Sb ₂ O ₃ component, and a known fining agent or defoaming agent in the field of glass production, or a combination thereof can be used.

The sum (molar sum) of the contents of the B ₂ O ₃ component and the SiO ₂ component is preferably 30.0% or more and 75.0% or less.
In particular, by setting this sum to 30.0% or more, it is possible to suppress a decrease in devitrification resistance due to the deficiency of the B ₂ O ₃ component or the SiO ₂ component. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 30.0%, more preferably 40.0%, further preferably 50.0%, further preferably 53.0%, further preferably 56. The lower limit is 0%.
On the other hand, by setting this sum to 75.0% or less, the decrease in the refractive index due to the excessive inclusion of these components can be suppressed, so that the desired high refractive index can be easily obtained. Therefore, the molar sum (B ₂ O ₃ + SiO ₂ ) is preferably 75.0% or less, more preferably less than 70.0%, further preferably less than 65.0%, further preferably less than 62.0%. .

The sum (molar sum) of the contents of the Rn ₂ O components (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 20.0% or less.
As a result, it is possible to suppress a decrease in the refractive index of the glass and reduce devitrification. Therefore, the molar sum of the content of the Rn ₂ O components is preferably 20.0% or less, more preferably less than 18.0%, further preferably less than 15.0%, further preferably less than 13.0%. .
On the other hand, if this sum exceeds 0%, the meltability of the glass raw material and the stability of the glass can be enhanced. Therefore, the total content of Rn ₂ O components is preferably more than 0%, more preferably more than 2.0%, further preferably more than 3.0%, further preferably more than 5.0%, further preferably 7. It may be more than 0%, more preferably more than 9.0%.

  The sum (molar sum) of the content of the RO component (in the formula, R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 10.0% or less. As a result, devitrification due to excessive inclusion of the RO component can be reduced, and a decrease in refractive index can be suppressed. Therefore, the total content of RO components is preferably 10.0%, more preferably 7.0%, further preferably 4.5% or less, and further preferably less than 3.0%.

RO component (in the formula, R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) and Rn ₂ O component (in the formula, Rn is selected from the group consisting of Li, Na, and K) 1 The sum (mol sum) of the contents of (more than one kind) is preferably 5.0% or more and 25.0% or less.
In particular, when the sum is 5.0% or more, the stability of the glass can be improved. Therefore, the molar sum (RO + Rn ₂ O) is preferably 5.0% or more, more preferably more than 7.0%, and further preferably more than 9.0%.
On the other hand, by setting this sum to 25.0% or less, the decrease in the refractive index can be suppressed. Therefore, the molar sum (RO + Rn ₂ O) is preferably 25.0% or less, more preferably less than 20.0%, still more preferably less than 17.0%, further preferably less than 16.0%, further preferably 12%. 0.7% or less.

The RO component (in the formula, R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) and the Rn ₂ O component (in the formula, relative to the total content of the B ₂ O ₃ component and the SiO ₂ component) The total content ratio (molar ratio) of Rn is one or more selected from the group consisting of Li, Na, and K), and is preferably 0.050 or more and 0.500 or less.
By adjusting this molar ratio, the stability of the glass can be increased and devitrification can be reduced. Therefore, the molar ratio (RO + Rn ₂ O) / (B ₂ O ₃ + SiO ₂ ) is preferably 0.050 or more, more preferably more than 0.070, and further preferably more than 1.000. The molar ratio (RO + Rn ₂ O) / (B ₂ O ₃ + SiO ₂ ) is preferably 0.500 or less, more preferably less than 0.400, further preferably less than 0.300, and further preferably 0.225. Below.

The ratio (molar ratio) of the content of the ZnO component to the sum of the contents of the ZnO component and the RO component (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba) is 0. .50 or more is preferable.
This makes it possible to lower the glass transition point while increasing the stability of the glass. Therefore, the lower limit of the molar ratio ZnO / (ZnO + RO) is preferably 0.50, more preferably 0.60, still more preferably 0.70, still more preferably 0.80.
On the other hand, the upper limit of this ratio may be 1.00.

The sum (molar sum) of the contents of the ZnO component and the ZrO ₂ component is preferably 10.0% or more and 35.0% or less.
In particular, by setting this sum to 10.0% or more, the stability of the glass and the refractive index can be increased. Therefore, the molar sum (ZnO + ZrO ₂ ) is preferably 10.0% or more, more preferably more than 15.0%, further preferably more than 18.0%, further preferably more than 20.0%, further preferably 21. 0% or more.
On the other hand, by setting this sum to 35.0% or less, devitrification due to excessive inclusion can be suppressed. Therefore, the molar sum (ZnO + ZrO ₂ ) is preferably 35.0% or less, more preferably less than 30.0%, further preferably less than 25.0%, further preferably less than 22.0%.

The sum (molar sum) of the contents of the ZnO component and the Li ₂ O component is preferably 10.0% or more and 40.0% or less.
In particular, by setting this sum to 10.0% or more, the glass transition point can be further lowered and the stability of the glass can be enhanced. Therefore, the molar sum (ZnO + Li ₂ O) is preferably 10.0% or more, more preferably more than 12.0%, further preferably more than 14.0%, further preferably more than 17.0%, further preferably 20%. The content is more than 0.0%, more preferably more than 23.0%, further preferably more than 25.0%.
On the other hand, by setting this sum to 40.0% or less, the decrease of the refractive index and the devitrification due to the excessive content can be suppressed. Therefore, the molar sum (ZnO + Li ₂ O) is preferably 40.0% or less, more preferably less than 35.0%, and further preferably less than 30.0%.

TiO ₂ component, the sum of the content of _Nb 2 _{O 5} component, and WO ₃ components (mol sum) is preferably 20.0% or less. As a result, it is possible to suppress lowering of the Abbe number of the glass and achieve low dispersion, and it is possible to reduce coloring and devitrification due to excessive inclusion of these components. Therefore, the molar sum (TiO ₂ + Nb ₂ O ₅ + WO ₃ ) is preferably 20.0% or less, more preferably less than 10.0%, further preferably less than 5.0%, further preferably less than 3.0%. And

<Ingredients that should not be contained>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferable to be contained will be described.

  Other components can be added, if necessary, within a range that does not impair the characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, except Ti, Zr, Nb, W, La, Gd, Y, Yb, and Lu, is used alone. Or, even if contained in a small amount in combination, the glass is colored and has the property of causing absorption at a specific wavelength in the visible region. Therefore, particularly in an optical glass using a wavelength in the visible region, it is preferable not to include substantially. .

Further, lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, and therefore it is desirable that they are not substantially contained, that is, they are not contained at all except inevitable mixing.

  Furthermore, the components Th, Cd, Tl, Os, Be, and Se have tended to be refrained from being used as harmful chemical substances in recent years, and are used not only in the glass manufacturing process but also in the processing process and post-commercial disposal. Environmental measures need to be taken. Therefore, when importance is attached to the influence on the environment, it is preferable that these are not substantially contained.

[Production method]
The optical glass of the present invention is produced, for example, as follows. That is, the above raw materials are uniformly mixed so that each component is within a predetermined content range, and the mixture thus prepared is charged into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted, and then a platinum crucible and a platinum alloy. Put in a crucible or iridium crucible, melt in a temperature range of 1100 to 1400 ° C for 3 to 5 hours, homogenize with stirring to eliminate bubbles, and then lower to a temperature of 1000 to 1300 ° C, and then perform finishing stirring to obtain a pulse. It is manufactured by removing the stress, casting in a mold and slowly cooling.

<Physical properties>
The optical glass of the present invention has a high refractive index and low dispersion (high Abbe number).
In particular, the lower limit of the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.60, more preferably 1.63, further preferably 1.65, and further preferably 1.67. The upper limit of this refractive index may be preferably 1.80 or less, more preferably less than 1.75, still more preferably 1.72 or less, still more preferably 1.70 or less, still more preferably 1.695 or less. . The Abbe number (ν _d ) of the optical glass of the present invention is preferably 40, more preferably 45, further preferably 48, further preferably 50, further preferably 52, as a lower limit, preferably 60, more preferably The upper limit is 58, more preferably 55.
The optical glass of the present invention has such a refractive index and an Abbe's number, and thus is useful in optical design, and can achieve downsizing of an optical system while achieving particularly high imaging characteristics and the like. The degree of freedom of can be expanded.

Here, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (νd) satisfy the relationship of (−0.01νd + 2.13) ≦ nd ≦ (−0.01νd + 2.33). In the glass having the composition specified in the present invention, a more stable glass can be obtained when the refractive index (nd) and the Abbe number (νd) satisfy this relationship.
Therefore, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (νd) satisfy the relationship of nd ≧ (−0.01νd + 2.13), and nd ≧ (−0.01νd + 2.17). It is more preferable to satisfy the relationship of nd ≧ (−0.01νd + 2.21).
On the other hand, in the optical glass of the present invention, it is preferable that the refractive index (nd) and the Abbe number (νd) satisfy the relationship of nd ≦ (−0.01νd + 2.33), and nd ≦ (−0.01νd + 2.29). ) Is more preferable, and the relation of nd ≦ (−0.01νd + 2.25) is more preferable.

The optical glass of the present invention preferably has a glass transition point of 600 ° C. or lower. Thereby, the glass softens at a lower temperature, so that the glass can be molded and press-molded at a lower temperature. Further, it is also possible to reduce the oxidation of the mold used for mold press molding and prolong the life of the mold. Therefore, the upper limit of the glass transition point of the optical glass of the present invention is preferably 600 ° C, more preferably 580 ° C, and further preferably 560 ° C.
The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 400 ° C, more preferably 450 ° C, and further preferably 500 ° C. Good.

The optical glass of the present invention preferably has a yield point (At) of 700 ° C. or lower. The yield point is one of the indexes indicating the softening property of glass, like the glass transition point, and is an index indicating a temperature close to the press molding temperature. Therefore, by using glass having a yield point of 700 ° C. or lower, press molding can be performed at a lower temperature, so that press molding can be performed more easily. Therefore, the yield point of the optical glass of the present invention is preferably 700 ° C, more preferably 650 ° C, and most preferably 630 ° C as an upper limit.
The yield point of the optical glass of the present invention is not particularly limited, but the lower limit may be preferably 500 ° C, more preferably 530 ° C, and further preferably 550 ° C.

The optical glass of the present invention preferably has a small average coefficient of linear expansion (α). In particular, the average linear expansion coefficient of the optical glass of the present invention is preferably 100 × 10 ⁻⁷ K ⁻¹ , more preferably 9 × 10 ⁻⁷ K ⁻¹ , and even more preferably 80 × 10 ⁻⁷ K ⁻¹ . And As a result, when the optical glass is press-molded with the molding die, the total amount of expansion and contraction due to the temperature change of the glass is reduced. Therefore, the optical glass can be made difficult to break during press molding, and the productivity of optical elements can be improved.

It is preferable that the optical glass of the present invention has a high visible light transmittance, in particular, a light transmittance of a short wavelength side of visible light, and thus a small amount of coloring.
In particular, the optical glass of the present invention has a wavelength (λ ₈₀ ) at which the sample having a thickness of 10 mm exhibits a spectral transmittance of 80% when expressed by the transmittance of the glass, preferably 450 nm, more preferably 420 nm, further preferably 400 nm. More preferably, the upper limit is 380 nm.
In the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 380 nm, further preferably 350 nm.
As a result, the absorption edge of the glass is in the ultraviolet region or in the vicinity thereof, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element such as a lens that transmits light.

The optical glass of the present invention preferably has a low specific gravity. More specifically, the specific gravity of the optical glass of the present invention is 4.50 or less. As a result, the mass of the optical element and the optical device using the same is reduced, which can contribute to the weight reduction of the optical device. Therefore, the upper limit of the specific gravity of the optical glass of the present invention is preferably 4.50, more preferably 4.20, and preferably 4.00. The specific gravity of the optical glass of the present invention is generally 3.00 or more, more specifically 3.20 or more, and more specifically 3.40 or more.
The specific gravity of the optical glass of the present invention is measured according to the Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method for measuring specific gravity of optical glass".

  The optical glass of the present invention is preferably a stable glass having a high devitrification resistance (sometimes referred to simply as “devitrification resistance” in the specification) during glass production. As a result, a decrease in transmittance due to crystallization of glass during glass production is suppressed, and thus this optical glass can be preferably used for an optical element such as a lens that transmits visible light. Note that a low liquidus temperature can be cited as a measure showing that the devitrification resistance during glass production is high.

[Glass molded article and optical element]
A glass molded product can be produced from the produced optical glass by using, for example, a polishing process means or a mold press molding means such as reheat press molding or precision press molding. That is, optical glass is subjected to mechanical processing such as grinding and polishing to produce a glass molded body, or preform produced from optical glass is subjected to reheat press molding and then polishing processing is performed to perform glass molding. A glass molded body can be manufactured by producing a body or performing precision press molding on a preform produced by performing a polishing process or a preform formed by known floating molding or the like. The means for producing the glass molded body is not limited to these means.

  As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs, and among them, it is particularly preferably used for optical elements such as lenses and prisms. As a result, it becomes possible to form a glass molded body with a large diameter. Therefore, while enlarging the optical element, high-definition and high-precision imaging characteristics and projection characteristics can be achieved when used in optical equipment such as cameras and projectors. The characteristics can be realized.

The composition of the embodiment of the present invention (Nanba1～nanba21) and Comparative Example (No. A), and a refractive index _(n d), Abbe number ([nu _d), the glass transition point (Tg) yield point ( At), average linear expansion coefficient (α), wavelengths (λ ₅ , λ ₈₀ ) at which the spectral transmittances are 5% and 80%, and specific gravity are shown in Tables 1 to 4.
It should be noted that the following embodiments are merely for the purpose of illustration, and the embodiments are not limited thereto.

  Each of the glasses of Examples and Comparative Examples is used as a raw material of each component in a usual optical glass such as a corresponding oxide, hydroxide, carbonate, nitrate, fluoride, hydroxide or metaphosphoric acid compound. A high-purity raw material is selected, weighed and uniformly mixed so that the composition ratios of the respective examples and comparative examples shown in the table are obtained, and then charged into a platinum crucible, depending on the melting difficulty of the glass composition. Melt in an electric furnace in the temperature range of 1100 to 1400 ° C. for 3 to 5 hours, homogenize by stirring to eliminate bubbles, and then reduce the temperature to 1000 to 1300 ° C. to homogenize by stirring, and then cast into a mold, Gradually cooled to produce glass.

The refractive index of the glass of the Examples and Comparative Examples _{(n d)} and Abbe number ([nu _d) was measured according to Japan Optical Glass Industry Society Standard JOGIS01-2003. Then, from the values of the obtained refractive index ( _nd ) and Abbe's number (ν _d ), the intercept b when the slope a was 0.01 in the relational expression n _d = −a × ν _d + b was obtained.
The glass used for this measurement was one that was treated in an annealing furnace at an annealing rate of -25 ° C / hr.

  The glass transition point (Tg) and the yield point (At) of the glasses of Examples and Comparative Examples are the temperature and the elongation of the sample according to the Japan Optical Glass Industry Association Standard JOGIS08-2003 “Method for measuring thermal expansion of optical glass”. It was determined from the thermal expansion curve obtained by measuring the relationship.

  The average linear expansion coefficient (α) of the glass of Examples and Comparative Examples was determined according to the Japan Optical Glass Industry Standard JOGIS08-2003 “Measuring method of thermal expansion of optical glass” at 100 to 300 ° C. .

The transmittances of the glasses of Examples and Comparative Examples were measured according to the Japan Optical Glass Industry Association Standard JOGIS02. In the present invention, the presence or absence and the degree of coloring of the glass were determined by measuring the transmittance of the glass. Specifically, a face-to-face parallel polished product having a thickness of 10 ± 0.1 mm was measured for spectral transmittance at 200 to 800 nm according to JIS Z8722, and λ ₅ (wavelength at 5% transmittance) and λ ₈₀ (transmittance) were measured. The wavelength at 80%) was determined.

  The specific gravities of the glass of Examples and Comparative Examples were measured based on Japan Optical Glass Industry Association Standard JOGIS05-1975 "Method of measuring specific gravity of optical glass".

As shown in these tables, the optical glass of the example of the present invention does not contain an expensive component, particularly a Ta ₂ O ₅ component, and can be obtained at a lower cost.

The optical glasses of Examples of the present invention are both refractive index _{(n d)} of 1.60 or more, with more particularly 1.67 or more, the refractive index _{(n d)} is 1.80 or less More specifically, it was 1.70 or less, which was within the desired range.

The optical glasses of the examples of the present invention each have an Abbe number (ν _d ) of 40 or more, more specifically 52 or more, and an Abbe number (ν _d ) of 60 or less, more specifically 55. It was below, and was within the desired range.

Further, the optical glass of the example of the present invention has a refractive index (nd) and an Abbe number (νd) satisfying the relationship of (−0.01νd + 2.13) ≦ nd ≦ (−0.01νd + 2.33). , More specifically, the relationship of (−0.01νd + 2.21) ≦ nd ≦ (−0.01νd + 2.25) was satisfied. The relationship between the refractive index (nd) and the Abbe number (νd) for the glass of the example of the present application is as shown in FIG.
Each of these optical glasses was a stable glass without devitrification.
Therefore, it is clear that the optical glass of the example of the present invention has a refractive index ( _nd ) and an Abbe's number (ν _d ) within desired ranges, and that an optical glass with high stability can be obtained. It was

Further, since the optical glass of the example of the present invention has a glass transition point of 600 ° C. or lower, more specifically 560 ° C. or lower, it is presumed that the glass can be mold press-molded at a lower temperature. The optical glass of the example of the present invention had a yield point of 700 ° C or lower, more specifically 600 ° C or lower.
On the other hand, the glass of the comparative example had a glass transition point of higher than 600 ° C.
Therefore, it was revealed that the optical glass of the example of the present invention has a lower glass transition point than the glass of the comparative example and is suitable for press molding. This is also inferred from the fact that the optical glass of the example of the present invention has a low yield point.

Accordingly, the optical glasses of Examples of the present invention is the refractive index (n _d) and Abbe number ([nu _d) is within the desired range is suitable for press-molding a low glass transition point, and a high stability It became clear.

In addition, the optical glasses of the examples of the present invention each had a λ ₈₀ (wavelength at a transmittance of 80%) of 450 nm or less, more specifically 380 nm or less. Further, the optical glasses of the examples of the present invention each had a λ ₅ (wavelength at a transmittance of 5%) of 400 nm or less, more specifically 330 nm or less.
Further, the optical glass of the example of the present invention had an average linear expansion coefficient (α) of 100 × 10 ⁻⁷ K ⁻¹ or less, more specifically 80 × 10 ⁻⁷ K ⁻¹ or less.
Further, the optical glasses of the examples of the present invention each had a specific gravity of 4.50 or less, more specifically 3.60 or less.

  From this, it can be inferred that the optical glass of the example of the present invention has a high transmittance for visible light and a small specific gravity and average linear expansion coefficient.

  Although the present invention has been described in detail above for the purpose of illustration, the present embodiment is merely for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the idea and scope of the present invention. Will be understood.

Claims (5)

Mol% based on oxide,
25.0% or more and 70.0% or less of B ₂ O ₃ component,
The sum (molar sum) of the contents of the Ln ₂ O ₃ component (wherein Ln is at least one selected from the group consisting of La, Gd, Y, and Yb) is 3.0% or more and less than 14.0% < br /> contains,
The content of Ta ₂ O ₅ component is less than 1.0%,
The content of Gd ₂ O ₃ component is less than 1.0%,
An optical glass having a refractive index (nd) of 1.60 or more and 1.80 or less and an Abbe number (νd) of 40 or more and 60 or less. Mol% based on oxide,
La ₂ O ₃ component 0 to less than 14.0%,
SiO ₂ component 0 to 20.0%,
Li ₂ O component 0 to 20.0%,
ZnO component 0 to 25.0%,
ZrO ₂ component 0 to 10.0%,
Y ₂ O ₃ component 0 to less than 10.0%,
Yb ₂ O ₃ component 0 to 10.0%,
Na ₂ O component 0 to 10.0%,
K ₂ O component 0 to 10.0%,
MgO component 0 to 10.0%,
CaO component 0 to 10.0%,
SrO component 0 to 10.0%,
BaO component 0 to 10.0%,
TiO ₂ component 0 to 20.0%,
Nb ₂ O ₅ component 0 to 15.0%,
WO ₃ component 0 to 10.0%,
P ₂ O ₅ component 0 to 15.0%,
GeO ₂ component 0 to 15.0%,
Al ₂ O ₃ component 0 to 15.0%,
Ga ₂ O ₃ component 0 to 15.0%,
Bi ₂ O ₃ component 0 to 10.0%,
TeO ₂ component 0 to 15.0%,
SnO ₂ component 0-5.0% and Sb ₂ O ₃ component 0-1.0%
The optical glass according to claim 1, which is   The optical glass according to claim 1 or 2, wherein the oxide-based molar ratio ZnO / (ZnO + RO) is 0.50 or more (wherein R is at least one selected from the group consisting of Mg, Ca, Sr, and Ba). ).   An optical element comprising the optical glass according to claim 1. A preform for polishing and / or precision press molding, comprising the optical glass according to any one of claims 1 to 3.

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